Do you have the small orifice or nozzle just after the valve that lets the pressurized water into the tee under the induction cone?  It needs a small volume of high velocity water forced into the tee to create a suction from the cone.  Also, it would probably work much better if it didn't have that short sweep elbow just after the tee which tends to make the high velocity jet of water from the orifice want to "kick back".